AN-6 or -8 for My Fuel System (SBF)

[Rory McNeil]

Maybe I`m just cheap & stupid, but a lot of these recommendations seem like overkill to me. First off, the origional poster said he is using a 780 Holley, which has 2 large float bowls, and 2 needle and seat assemblies, so it is not as hard to keep the carb full, compared to a Q Jet.
Both my cars have Holley "Blue" pumps and regulators, and have been reliable and adequate for many years.
My 427 FE Ford bracket car has a 780 Holley and runs 9.9-10.0s at 132MPH with the same blue Holley setup and 1/2" hard line since I started running the car over 25 years ago, and my Stocker 85 Mustang has had the same blue pump and reg, with 3/8" hard line and stock gas tank for 11 years. This setup has been fine even with my bracket engine, which has gone 10.3 @128 MPH with a Holley 650, and was obviously more than adequate for the much slower Stocker engine. I`m not saying that spending over a grand on a fuel system is a bad thing, if you don`t mind spending the $$$$, but at least with a Holley carb, there are cheaper setups that will work

[Adger Smith]

Take the jets in the carb + the PVCR and figure the total area.
Then take the sizes of the needle & seats. Figure that area.
The two total areas should be close to equal.
Then take a Blue Holley Regulator apart and measure the size of the hole in it. Then figure the area. But wait to get the actual area you need to subtract the area of the pin from the diaphragm that works through the hole & pushes on the check ball. (that pin is a restriction) The flow of you system should more than match what you are flowing at the carb. Area is not the real way to figure it, but is the easy way & is close enough for our use. If it isn't right it could cause float levels to change and down track performance be affected. BTW check the size of the pump inside, too.

[Chad Rhodes]

I've never seen too much fuel system slow a car down.

[Bill Edgeworth]

Originally Posted by Chad Rhodes

I've never seen too much fuel system slow a car down.

I have, if I get some time a little later in the day I will explain.

[FED 387]

also while we are at it depending on the type of material your float is made of you just might not have the float set at the correct level causing improper engine performance due to lack of fuel-- look into it its something that does happen from time to time

[FireSale]

Current wish list.

-10 braided line
MagnaFuel filter
MagnaFuel Quick Star 275 pump
MagnaFuel regulator
Holley pressure gauge
Summit 15 gal aluminum fuel cell and straps
AN hose cutters and Koul AN installation tool for -10

Total damages: $1,044

The pump maxes out at 18psi which is twice what a carb motor needs. It's rated to feed up to 700 hp and I hope for around 500. It's also been used on the street, so I wouldn't worry about burning it out driving to the strip this year towing a small trailer.

There seem to be two return systems, one from the pump and one from the carb feed. One is a closed pressurized line at the carb and the other is a loop back to the tank. Most big pumps return from the pump. Any preferences here?

Thanks for all the feedback and well thought out PMs.

Dale

[HandOverFist]

Ours has -10 from tank to regulator and -8 from there to carb. Using a BG 280 pump it shows 14psi on the high side then goes thru a big body Holley regulator which is set to 6-1/2psi. I have not seen it drop pressure down track as of yet. Recently added a gauge on the cowl to confirm this...who knows if it is really accurate/responsive enough to show tho.

[FireSale]

Originally Posted by HandOverFist

Ours has -10 from tank to regulator and -8 from there to carb. Using a BG 280 pump it shows 14psi on the high side then goes thru a big body Holley regulator which is set to 6-1/2psi. I have not seen it drop pressure down track as of yet. Recently added a gauge on the cowl to confirm this...who knows if it is really accurate/responsive enough to show tho.

Thanks for the input. I really hope you can keep your rig up and running for the season and beyond. Reading your build thread has been painful.

Dale

[V M Kauffman]

You need 7.5 lb of pressure to move the column of fuel for each G of acceleration this is just to move fuel forward if the fuel cell is in the rear

Originally Posted by FireSail

Thanks for the input. I really hope you can keep your rig up and running for the season and beyond. Reading your build thread has been painful.

Dale

[FireSale]

Originally Posted by V M Kauffman

You need 7.5 lb of pressure to move the column of fuel for each G of acceleration this is just to move fuel forward if the fuel cell is in the rear

I read that too. Lateral acceleration doesn't translate well into G forces which are a pull against gravity. A Top Fuel car will pull something like 4 G so a 10,000 hp engine would need something like a 40 psi pump.

If the line was empty at launch, then there would be a force working against the pump, but since the system is fully pressurized I don't think this is that much of an issue. The force of launch could actually aide the pump. The fuel would be pushed to the back of the tank and out the exit line towards the pump forcing fuel into the system.

Dale